The physical memory of a computer, i.e., random access memory (“RAM”), consists of a number of cells which store information. These cells are referred to as addresses. Programs access the memory by referring to an address space. If a memory cell consists of N bits, it can hold 2N different bit combinations. Thus, if a memory cell consists of 32 bits, it can hold 232 different bit combinations. A program written for a 32-bit memory addressing scheme may access 232 memory addresses, the equivalent of four gigabytes of RAM.
Most conventional programs follow a 32-bit addressing model. Thus, if a computer has more than four gigabytes of RAM, the processor cannot directly address all of the physical memory without using complicated memory access schemes. The same access problems may occur when accessing files maintained in a secondary storage device, e.g., a database maintained on a hard disk, which is larger than four gigabytes.
Programs originally written according to a 32-bit addressing model are unable to make calls to, or directly address, a larger address space without rewriting the source code, a time consuming and daunting task, or using complex addressing schemes. Rewriting the source code is possible only if the original source code is available.
Accordingly, a need exists for a manner of adapting source code written for a 32-bit addressing model to execute on machines having an address space larger than four gigabytes.